Elastic printed conductors

ABSTRACT

The development of stretchable, mechanically and electrically robust interconnects by printing an elastic, silver-based composite ink onto stretchable fabric. Such interconnects can have conductivity of 3000-4000 S/cm and are durable under cyclic stretching. In serpentine shape, the fabric-based conductor is enhanced in electrical durability. Resistance increases only ˜5 times when cyclically stretched over a thousand times from zero to 30% strain at a rate of 4% strain per second due to the ink permeating the textile structure. The textile fibers are wetted with composite ink to form a conductive, stretchable cladding of the silver particles. The e-textile can realize a fully printed, double-sided electronic system of sensor-textile-interconnect integration. The double-sided e-textile can be used for a surface electromyography (sEMG) system to monitor muscles activities, an electroencephalography (EEG) system to record brain waves, and the like.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/682,022 filed Jun. 7, 2018, whichis incorporated herein by reference.

BACKGROUND OF THE INVENTION

Wearable health care electronics are developed to ultimately integratewith daily textiles and clothes, so that the wearable electronics can befeatured with the fabrics' unique characteristics of skin comfort,softness, thermal dissipation, breathability, light weight, and highconformability (1,2,3). Fabric-based electronics, also known as known as‘e-textiles’, are emerging as a next-generation class in whichelectronics are built on textile fibers (4,5,6,7,8,9). E-textiles areinspiring a number of research efforts for biomedical and health careassessment (1,10). In the vision of fully integrated e-textile systems,fundamental flexible electronics like semiconducting transistors(11,12), processing units (13,14), sensors (15,16,17,18,19,20),generators (21,22,23,24,25), and energy storage units (26,27) would bedeveloped toward integration onto or into textiles. In the last decade,the reported research efforts have employed several strategies forrealizing smart e-textiles such as (i) integrating electronic units onto2D fabric substrates (8,21,28), and (ii) interweaving 1D thread-likeelectrode devices into fabric structures (29). The latter strategy islimited in miniaturization and flexibility since the electronic threads,consisting of various functional layers, are prone to mechanicalstiffening, un-conformability, and adverse interconnection betweenmulti-thread and signal acquisition electronics. For such reasons,e-textiles with electronics embedded on 2D fabric substrates arestrategically developed in a large spectrum of applications.

The recent breakthroughs in thin-film flexible devices have providedhigh-resolution biophysiological measurements such as electrical signals(30,31), electrochemical signals from sweat (32), temperature (33,34),tactile force (35), and blood glucose (36). E-textile systems can berealized by embedding these thin-film devices on textiles to takeadvantages of the high-performance electronics. To achieve a fullyintegrated e-textile, stretchable interconnects/wirings are central inorder to stably connect the prefabricated thin devices and textiles.Several fabric-based wires have been used such as (i) knitting orweaving 1D conductive threads into textiles (37), (ii) fully coating 2Dtextile sheets with conductive materials (38), and (iii) stencil andscreen printing conductive ink on textiles (39). In recent reportedworks (39,40), viscous composite inks were printed via a patternedstencil onto a textile sheet to form stretchable wires which are low insurface resistivity of 0.06 Ωsq⁻¹. However, despite permeation of thecomposite ink into the textile by using certain solvents, theink-textile wires still needed multiple-layered printing (5 overlays)and high-temperature (160° C.) pressing to be capable of cyclicstretching up to 1000 times with an increase of one-order in resistance(from zero to 10% strain). Such hot-press processing, however, wouldhasten thermal degradation of most of daily fabrics, with a significantdecrease in performance when treated between the temperature range of125° C.-180° C. (41).

SUMMARY

In this work, we develop a stretchable, mechanically and electricallyrobust e-textile that fully integrates sensors and interconnects byprinting silver-based composite ink onto stretchable fabric (FIG. 1).The printed, textile-based conductors have high conductivity (3000-4000S/cm), and are able to stretch more than 100% in uniaxial strain withone-order increase in resistance. Furthermore, when laid out in aserpentine shape, the textile-based interconnect demonstrates enhancedelectrical durability as it only increases ˜5 times in resistance whencyclically stretched over a thousand times from zero to 30% strain at arate of 4% strain per second. Such enhancement is possible due to the‘wetting’ of the textile fibers with composite ink to form a conductive,stretchable cladding of the silver particles along the fibers. Wefurther use the textile-based conductors to manufacture monitoringsystems for (i) surface electromyography (sEMG) sensing of human musclesactivities, and (ii) electroencephalography (EEG) sensing of human brainwaves. These textile-based biosensors adhered and conformed well to theskin for high quality biosensing applications.

Accordingly, this disclosure provides an electronic textile apparatuscomprising:

a) a porous textile having fibers, a surface and an opposite surface;

b) a patterned electrically conductive wire that coats a portion of thefibers at the surface of the textile;

c) an electrode that coats a portion of the fibers at the oppositesurface of the textile; and

d) an electrically conductive interconnect that coats a portion of thefibers within the textile, disposed between the surface and the oppositesurface of the textile, and in contact with the wire and the electrode;

wherein the wire, the electrode and the interconnect comprise anelastomer and metal particles.

This disclosure also provides an ink composition comprising about 1 partto about 5 parts of a fluorocopolymer (a), about 1 part to about 5 partsof an organic solvent (b), and about 1 part to about 5 parts of metalflakes (c).

Additionally, this disclosure provides a method for fabricating astretchable electronic textile from the ink composition above,comprising:

a) printing a circuit with the ink composition on a porous textilehaving fibers;

wherein a wire is printed on a surface of the textile, and an electrodeis printed on the opposite surface of the textile;

b) inserting the ink composition into the textile to provide anelectrical contact between the wire and the electrode, thereby forming acompleted circuit;

c) drying the completed circuit;

wherein the printable ink coats a portion of the fibers that forms thecompleted circuit, and the textile has an electrical resistance ratio ofabout 10 or less than 10 after about 1000 cyclic stretches from zero toabout 30% strain at a rate of about 4% strain per second.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the specification and are includedto further demonstrate certain embodiments or various aspects of theinvention. In some instances, embodiments of the invention can be bestunderstood by referring to the accompanying drawings in combination withthe detailed description presented herein. The description andaccompanying drawings may highlight a certain specific example, or acertain aspect of the invention. However, one skilled in the art willunderstand that portions of the example or aspect may be used incombination with other examples or aspects of the invention.

FIG. 1. Printed, stretchable fabric conductors.

FIG. 2. Stretchable fabric-based interconnects by printed Ag-particlecomposite onto electro-spun polyurethane textile.

FIG. 3. Two-sided printed fabric devices with EMG sensors and serpentineinterconnects.

FIG. 4. Fully integrated e-textile sEMG devices for real-time monitoringmuscle activities.

FIG. 5. sEMG measurements of muscles activities.

FIG. 6. Viscous ink printing setup and apparatus, including sample ink,loaded syringe, printer, and resultant printed textile.

FIG. 7. A composite ink vs. commercial ink.

FIG. 8. Serpentine interconnects.

FIG. 9. Failure of commercial ink.

FIG. 10. Metal flake size and permeation effect.

FIG. 11. One embodiment of one-step printing process.

FIG. 12. Effect of heatless compression treatment on e-textile.

FIG. 13. E-Textile strain sensing performance characteristics.

DETAILED DESCRIPTION

Fabrication of our e-textile is simple and is manufactured in a one-stepprinting process without post-treatment (see FIG. 1(a), and FIG. 11). Weprinted a composite ink on a stretchable, nonwoven polyurethane (PU)fiber substrate. The full printed e-textile with interconnects andsensors is inherent of conformality, breathability, and flexibility (seeFIG. 1(b)). The printing is a rapid process, and capable ofmass-production. After one-step printing, the specimens are dried inroom condition. Details of the manufacturing process are discussedbelow.

Definitions

The following definitions are included to provide a clear and consistentunderstanding of the specification and claims. As used herein, therecited terms have the following meanings. All other terms and phrasesused in this specification have their ordinary meanings as one of skillin the art would understand. Such ordinary meanings may be obtained byreference to technical dictionaries, such as Hawley's Condensed ChemicalDictionary 14^(th) Edition, by R. J. Lewis, John Wiley & Sons, New York,N.Y., 2001.

References in the specification to “one embodiment”, “an embodiment”,etc., indicate that the embodiment described may include a particularaspect, feature, structure, moiety, or characteristic, but not everyembodiment necessarily includes that aspect, feature, structure, moiety,or characteristic. Moreover, such phrases may, but do not necessarily,refer to the same embodiment referred to in other portions of thespecification. Further, when a particular aspect, feature, structure,moiety, or characteristic is described in connection with an embodiment,it is within the knowledge of one skilled in the art to affect orconnect such aspect, feature, structure, moiety, or characteristic withother embodiments, whether or not explicitly described.

The singular forms “a,” “an,” and “the” include plural reference unlessthe context clearly dictates otherwise. Thus, for example, a referenceto “a compound” includes a plurality of such compounds, so that acompound X includes a plurality of compounds X. It is further noted thatthe claims may be drafted to exclude any optional element. As such, thisstatement is intended to serve as antecedent basis for the use ofexclusive terminology, such as “solely,” “only,” and the like, inconnection with any element described herein, and/or the recitation ofclaim elements or use of “negative” limitations.

The term “and/or” means any one of the items, any combination of theitems, or all of the items with which this term is associated. Thephrases “one or more” and “at least one” are readily understood by oneof skill in the art, particularly when read in context of its usage. Forexample, the phrase can mean one, two, three, four, five, six, ten, 100,or any upper limit approximately 10, 100, or 1000 times higher than arecited lower limit.

As will be understood by the skilled artisan, all numbers, includingthose expressing quantities of ingredients, properties such as molecularweight, reaction conditions, and so forth, are approximations and areunderstood as being optionally modified in all instances by the term“about.” These values can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings of the descriptions herein. It is also understood that suchvalues inherently contain variability necessarily resulting from thestandard deviations found in their respective testing measurements. Whenvalues are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value without themodifier “about” also forms a further aspect.

The terms “about” and “approximately” are used interchangeably. Bothterms can refer to a variation of ±5%, ±10%, ±20%, or ±25% of the valuespecified. For example, “about 50” percent can in some embodiments carrya variation from 45 to 55 percent, or as otherwise defined by aparticular claim. For integer ranges, the term “about” can include oneor two integers greater than and/or less than a recited integer at eachend of the range. Unless indicated otherwise herein, the terms “about”and “approximately” are intended to include values, e.g., weightpercentages, proximate to the recited range that are equivalent in termsof the functionality of the individual ingredient, composition, orembodiment. The terms “about” and “approximately” can also modify theendpoints of a recited range as discussed above in this paragraph.

As will be understood by one skilled in the art, for any and allpurposes, particularly in terms of providing a written description, allranges recited herein also encompass any and all possible sub-ranges andcombinations of sub-ranges thereof, as well as the individual valuesmaking up the range, particularly integer values. It is thereforeunderstood that each unit between two particular units are alsodisclosed. For example, if 10 to 15 is disclosed, then 11, 12, 13, and14 are also disclosed, individually, and as part of a range. A recitedrange (e.g., weight percentages or carbon groups) includes each specificvalue, integer, decimal, or identity within the range. Any listed rangecan be easily recognized as sufficiently describing and enabling thesame range being broken down into at least equal halves, thirds,quarters, fifths, or tenths. As a non-limiting example, each rangediscussed herein can be readily broken down into a lower third, middlethird and upper third, etc. As will also be understood by one skilled inthe art, all language such as “up to”, “at least”, “greater than”, “lessthan”, “more than”, “or more”, and the like, include the number recitedand such terms refer to ranges that can be subsequently broken down intosub-ranges as discussed above. In the same manner, all ratios recitedherein also include all sub-ratios falling within the broader ratio.Accordingly, specific values recited for radicals, substituents, andranges, are for illustration only; they do not exclude other definedvalues or other values within defined ranges for radicals andsubstituents. It will be further understood that the endpoints of eachof the ranges are significant both in relation to the other endpoint,and independently of the other endpoint.

One skilled in the art will also readily recognize that where membersare grouped together in a common manner, such as in a Markush group, theinvention encompasses not only the entire group listed as a whole, buteach member of the group individually and all possible subgroups of themain group. Additionally, for all purposes, the invention encompassesnot only the main group, but also the main group absent one or more ofthe group members. The invention therefore envisages the explicitexclusion of any one or more of members of a recited group. Accordingly,provisos may apply to any of the disclosed categories or embodimentswhereby any one or more of the recited elements, species, orembodiments, may be excluded from such categories or embodiments, forexample, for use in an explicit negative limitation.

The term “contacting” refers to the act of touching, making contact, orof bringing to immediate or close proximity, including at the cellularor molecular level, for example, to bring about a physiologicalreaction, a chemical reaction, or a physical change, e.g., in asolution, or in a reaction mixture.

The term “substantially” as used herein, is a broad term and is used inits ordinary sense, including, without limitation, being largely but notnecessarily wholly that which is specified. For example, the term couldrefer to a numerical value that may not be 100% the full numericalvalue. The full numerical value may be less by about 1%, about 2%, about3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about10%, about 15%, or about 20%.

A “solvent” as described herein can include water or an organic solvent.Examples of organic solvents include hydrocarbons such as toluene,xylene, hexane, and heptane; chlorinated solvents such as methylenechloride, chloroform, and dichloroethane; ethers such as diethyl ether,tetrahydrofuran, and dibutyl ether; ketones such as acetone, 2-butanone,and 3-pentanone; esters such as ethyl acetate and butyl acetate;nitriles such as acetonitrile; alcohols such as methanol, ethanol, andtert-butanol; and aprotic polar solvents such as N,N-dimethylformamide(DMF), N,N-dimethylacetamide (DMA), and dimethyl sulfoxide (DMSO).Solvents may be used alone or two or more of them may be mixed for useto provide a “solvent system”.

Embodiments of the Invention

This disclosure provides an electronic textile apparatus comprising:

a) a porous textile having fibers, a surface and an opposite surface;

b) a patterned (e.g., serpentine patterned) electrically conductive wirethat coats a portion of the fibers at the surface of the textile;

c) an electrode that coats a portion of the fibers at the oppositesurface of the textile; and

d) an electrically conductive interconnect that coats a portion of thefibers within the textile, disposed between the surface and the oppositesurface of the textile, and in contact with the wire and the electrode;

wherein the wire, the electrode and the interconnect comprise anelastomer and metal particles.

In additional embodiments, a textile is a plasma-treated textile, aporous plasma-treated textile, or a porous plasma-treated nanotextile.In other additional embodiments the patterned electrically conductivewire is a serpentine patterned electrically conductive wire. In yetother embodiments the patterned electrically conductive wire can be anypattern that can adapt to the contours of any shape.

In various embodiments, the fibers comprise electrospun polyurethane. Inadditional embodiments, the textile has a pore size of about 1 micron toabout 100 microns. In other embodiments, the surface and the oppositesurface of the textile has coated fibers up to a depth of about 100microns within the textile.

In various additional embodiments, the elastomer is a fluoropolymer or afluorocopolymer. The fluoropolymer can be, for example, poly(vinylidenefluoride). The average molecular weight M_(w) of the fluoropolymer canbe about 400 kDa to about 700 kDa, about 500 kDa to about 600 kDa, orabout 534 kDa (e.g., as determined by GPC). The fluorocopolymer can be,for example, poly(vinylidene fluoride-co-hexafluoropropylene), as shownin FIG. 1(e) wherein x and y are values such that the average molecularweight M_(w) is about 200 kDa to about 600 kDa. The average molecularweight M_(w) of the fluorocopolymer can also be 300 kDa to about 500kDa, about 350 kDa to about 500 kDa, about 400 kDa, or about 450 kDa(e.g., as determined by GPC).

In various embodiments, the metal particles have a diameter of up toabout 10 microns, for example, about 100 nm to about 10 microns, about200 nm to about 10 microns, about 500 nm to about 5 microns, or about 5microns to about 10 microns. To ensure effectiveness, the average metalparticle size employed for a particular application should be less thanthe pore size of the textile substrate to which it is applied.Accordingly, in various embodiments, the metal particle size is smallerthan the pore size of textile substrate. The Ag-particle size affectsthe depth of the ink permeation. The permeation of the printed ink canbe optimized by employing suitable metal particle sizes.

In some embodiments the metal particles are transition metal particles,transition metal nanoparticles, transition metal flakes, or transitionmetal nanoflakes. In some embodiments, a fabric, fiber, particlecomposite, composite ink, textile, flake, pore, and clad can be (or areinterchangeable with the terms) a nanofabric, nanofiber, nanoparticlenanocomposite, nanocomposite ink, nanotextile, nanoflake, nanopore, andnanoclad, respectively.

In other additional embodiments, the textile has an electricalresistance ratio of about 10 or less than 10 after about 1000 cyclicstretches from zero to about 30% strain at a rate of about 4% strain persecond.

This disclosure additionally provides an ink composition comprisingabout 1 part to about 5 parts of (a) a fluorocopolymer, about 1 part toabout 5 parts of (b) an organic solvent, and about 1 part to about 5parts of (c) metal flakes. In various embodiments, the composition has aratio of a:b:c of about 4:3:3. In additional embodiments, the metalflakes are silver flakes having a diameter of about 200 nm to about 10microns, or about 1 micron to about 10 microns. In some otherembodiments, the organic solvent is a ketone. In other embodiments, thecopolymers disclosed herein can comprise random or block copolymers.

This disclosure also provides a method for fabricating a stretchableelectronic textile from an ink composition described above or herein,comprising:

a) printing a circuit with the ink composition on a porous textilehaving fibers;

wherein a wire is printed on a surface of the textile, and an electrodeis printed on the opposite surface of the textile;

b) inserting the ink composition into the textile to provide anelectrical contact between the wire and the electrode, thereby forming acompleted circuit;

c) drying the completed circuit;

wherein the printable ink coats a portion of the fibers that forms thecompleted circuit, and the textile has an electrical resistance ratio ofabout 10 or less than 10 after about 1000 cyclic stretches from zero toabout 30% strain at a rate of about 4% strain per second.

In some embodiments, the fibers are electrospun polyurethane and thetextile has a pore size of about 1 micron to about 100 microns. In yetother embodiments, the completed circuit comprises a circuit for awearable medical device. In various embodiments the completed circuitcomprises a circuit for sensing surface electromyography (sEMG),electromyography (EMG), electroencephalography (EEG),electrocardiography (ECG), electrooculography (EOG), respiratory rate,heart rate, mechanical strain, pressure, temperature, or vibration.

This disclosure provides additional embodiments of the disclosede-textiles, including but not limited to, applications or use inelectromyography (EMG), surface electromyography (sEMG),electroencephalography (EEG), electrocardiography (ECG),electrooculography (EOG), and other embodiments for respiratory rate,heart rate, mechanical strain, pressure, temperature, and vibration.This disclosure provides ranges, limits, and deviations to variablessuch as volume, mass, percentages, ratios, etc. It is understood by anordinary person skilled in the art that a range, such as “number1” to“number2”, implies a continuous range of numbers that includes the wholenumbers and fractional numbers. For example, 1 to 10 means 1, 2, 3, 4,5, . . . 9, 10. It also means 1.0, 1.1, 1.2. 1.3, . . . , 9.8, 9.9,10.0, and also means 1.01, 1.02, 1.03, and so on. If the variabledisclosed is a number less than “number10”, it implies a continuousrange that includes whole numbers and fractional numbers less thannumber10, as discussed above. Similarly, if the variable disclosed is anumber greater than “number10”, it implies a continuous range thatincludes whole numbers and fractional numbers greater than number10.These ranges can be modified by the term “about”, whose meaning has beendescribed above.

Results and Discussion

In one example we used commercially available non-woven textile ofelectrospun polyurethane nanofibers, which are hydrophilic,thermoplastic, nonwoven electro-spun polyurethane (PU) fiber matrices.FIG. 1(c) shows a top-view scanning electron microscope (SEM) image ofthe PU textile. The fibers have diameters from one-order to four-ordernanometers. There is a large number of pores within the fiber matrix.Such highly porous matrix allows the textile to have the abilities ofhigh breathability, and absorbency from 2.5 to 18.5 g/g (i.e., absorbedliquid/textile in mass) when soaked in saline solution (0.9% NaCl inwater) for 30 minutes when measured by following the NWSP 240.0.R2 (15)standard test (Technical Datasheet of SNS Nanosan®-Sorb material (42)).This PU textile is mainly used in medical applications as sweat andblood absorbent. Moreover, the textile has a stretchability up to 250%and good recovery below 50% when uniaxially strained.

The composite ink was prepared by mixing conductive silver flakes intofluoroelastomer matrix which is dissolved in methyl ethyl ketone (MEK)(or also known as butanone) as seen in FIG. 1(d). In literature, similarsilver/fluoroelastomer composite inks were also reported for makingstretchable conductors [cite Someya, Amit]. Firstly, the fluoroelastomer(obtained as DAI-EL® G-801 from DAIKIN AMERICA, Inc.) was dissolved inMEK in 24 hours. Then, silver flakes (obtained from Sigma Aldrich,average particle size of 2-3.5 microns) was added to the solution andstirred for 8 hours. The viscosity and conductivity of the composite inkdepend on the concentration of the fluoroelastomer, and fraction ofsilver flakes. In one example of our work, the weight ratio offluoroelastomer:MEK:silver flakes was chosen as 4:3:3. Each integer ofthis ratio can independently be increased or decreased by one or twointegers to provide other suitable ratios.

For printing, the textile substrate with thickness of 300 microns waspre-treated in a plasma chamber for 10 minutes. The prepared viscous inkwas loaded to a syringe of jet-printing system (commercial product asnScrypt Tabletop-3Dn printer). Ink droplets were expelled via a150-micron nozzle under a pressure of 10 kPa relative to air pressure.Upon depositing on the textile substrate, the ink microdroplets wereabsorbed from the surface to the inside structure of textile.Interestingly, the hydrophilic fibers were wetting with the viscous ink,which then dried to form a very thin coating layer of ink along thefibers as shown in FIG. 1(e-i). Printed conductors were dried at roomtemperature of 22° C. in a fume hood for 8 hours. FIG. 1(g) shows thatthe ink-printed structure had roughly a total thickness of 140 microns,of which comprising of two parts such as (i) an 80-micron-thick layeratop the textile surface, and (ii) another 60-micron-depth permeatedlayer inside the textile. For the permeated part, the silverflake/fluoroelastomer composite ink formed coating clads of the fibersas shown in illustration of FIG. 1(f). The coating clads were observedto have an average thickness in sub-micron dimension, in which thesilver flakes continuously aligned to create intrinsically stretchableconductive paths along the fibers, as shown in the SEM image (FIG.1(h)). Such conductive cladded fiber interconnects can benefit themechanical durability, conductivity, and adhesion of conductors to thetextiles. These advantages play key roles in performance of e-textileswhen integrated to a full electronic system. In another example theprinting process as described above was demonstrated on commerciallyavailable woven Nylon and Spandex textile substrates. No marked changein printing performance or overall e-textile performance characteristicswere observed.

Effects of Ag particles on permeation of composite ink into textiles. Weused two species of Ag particles with different shapes and particlesizes, including: i) flakes with the size of about 10 μm metal traces(denoted as Ag flakes hereafter) and ii) powders with size of about2-3.5 μm metal traces (denoted as Ag powders). The size values arestated as specified by the vendor (Sigma-Aldrich); however, the actualsize distribution of individual particles (flakes or powders) wasextremely polydisperse in nature. Especially, the existence of nanosizedparticles seems to affect the properties of e-textiles. The SEM image ofthe Ag flakes reveal that each particle is predominantly larger than amicrometer in size with irregular shapes (FIG. 10a ), whereas manyparticles in the Ag powders had sizes around (or even less than) 200 nm(FIG. 10b ). These small particles efficiently permeate into the poresof the textile substrate, resulting in the formation of cladded-layershown in FIG. 1f, h . FIG. 10c,d shows the cross-section of the printedinks (i.e., Ag particles with fluoropolymers after solvents were dried).The printed ink containing Ag flakes showed distinctively smallerthickness of cladded-layer (FIG. 10c ) when compared to the printed inkwith Ag powders (FIG. 10d ).

In our experiment, viscosity, ink-jetting parameters, and solvent dryingrate were essentially the same for the two types of inks, but thepermeation depth showed a stark difference. Additionally, when compositematerials are printed into a porous substrate, one must take the sizeeffect of printing particles and the pores in the substrate intoaccount. As shown in FIG. 10c,d , Ag-powder-based ink contains manysmall-sized particles that can freely pass through the pores openingthrough the forest of nanosized fibers in the substrate, whereasAg-flake-based ink does not. As a result, the Ag-powder-based ink wasable to form a cladded layer of around 60 μm in thickness (FIGS. 1h and10), whereas that of Ag-flake-based ink was only around 10 μm thick(FIG. 10c ). We believe that such geometric effect dictated thedifference in the permeation depth of the wet ink, which finally causedthe thickness of the cladded-layer.

Electrical and Mechanical Characteristics. We studied the mechanical andelectrical performance of the cladded interconnects by printing the inkon the textile for two different designs such as a narrow rectangularstrip, and a serpentine line as shown in FIG. 2(a, b). In addition,commercial silver ink with silver particle size more than 10 microns wasalso printed on the same textile for comparison (see FIG. 7). Thedimension of the narrow strip as 1 mm width and 40 mm length, and thatof the serpentine line was 0.5 mm linewidth, 2 mm lateral amplitude, 40mm length, and 2 mm pitch interval (FIG. 8).

FIG. 2(c) shows the change in resistance under uniaxial strains fromzero to 125% of four printed conductors which are named as Type A and Bfor a narrow strip and a serpentine line of the composite ink, and TypeC and D for the same designs of the commercial ink. The printedcomposite ink has demonstrated better electrical properties than thecommercial ink did (FIG. 2(c)). The relative resistance ratio of thecomposite ink increased 412 times at 60% strain for Type A, and 24.7times at 120% strain for Type D. For the commercial ink, the resistanceratio increased 1000 times at 30% strain for Type C, and 920 times at100% strain for Type D. It was observed that the serpentine samples haveenhanced the electrical properties under stretching for both printedconductors, i.e. composite and commercial inks.

The printed samples of the composite ink were tested under 5stretching-releasing cycles of uniaxial tensile strains from 0% to 50%.As shown in FIG. 2(d), hysteresis is observed for the fiveloading-unloading cycles for the printed narrow strip. However, for theserpentine sample, after the first cycle, the hysteresis reduced to benegligible. Similar behavior was also observed for the pristine textilestrip. In addition, both the printed samples, i.e. narrow strip andserpentine line, showed 100% self-recovery without distinct yielding inthe stretching-releasing cycle. Therefore, it indicates that the printedsamples would have high fatigue resistance, or mechanical durability.FIG. 2(e) shows cyclic durability of the electrical properties of thecomposite serpentine lines under a thousand loading-unloading cycles of10%, 20%, and 30% stretching with a rate of 4%/second. The resistancegradually increased with the number of stretching cycles. However, therelative ratio of resistance was maintaining at small value below 10times for all of the cyclic stretching values of 10%, 20%, and 30%. Suchperformance was achievable due to the well cladding of the composite inkand the fibers, and the enhanced stretchability of the serpentine shape(FIG. 2(f, g)).

Stretchable, Two-Sided Integration E-Textiles. The printed ink whichconsisted of a part atop the textile surface and another part claddingthe fiber was a stretchable and robust textile-based conductor. It isobserved that the ink permeated partly into the textile so that thefiber cladding depth was around a quarter of the textile thickness asseen in FIG. 1(g). We exploited this to make a fully printed, two-sidee-textile of biosensors as shown in FIG. 3. The biosensors consisted ofelectrodes and serpentine interconnects that were printed on oppositesides of the textile. Utilizing the porous textile structure, narrowconductive channels were embedded inside the textile to be top-to-bottominterconnects between the electrodes and the on-surface interconnects asshown in FIG. 3(a, b). The narrow channels were formed by injecting asmall amount of the ink into the textile spacer between the electrodesand the serpentine interconnects via a needle (0.3 mm diameter). FIGS.3(c) and (d) shows the SEM images of the cross sections of the printedelectrode and the narrow conductive channel.

Moreover, e-textiles that have electrodes and wires on the same side areprone to suffer ink cracking at the electrode-interconnect junction asshown in FIG. 9. This issue happens due to the mismatch in stiffnesssince the electrodes are large-area pads and stiffer than the serpentineinterconnects. Therefore, the two-sided e-textile resolves the unstableconnection. The narrow channels are intrinsically stretchable so that itbenefits a stable connection between the electrodes and the wires. FIG.3 (e, f) shows that the fully integrated two-sided e-textiles are underharsh stretching. The e-textile biosensors were conformally attachedonto skin by a medical double-sided adhesive tape. For direct contact ofelectrode-to-skin and breathability, the adhesive tape was patternedwith several cut-through circles (FIG. 3(g, h)).

Squeezed, One-Sided Construct of E-Textile for Enhanced Stretchabilityin Selected Areas. In selected areas of the aforementioned sample, it isadvantageous to apply compressive pressure (squeezing) for 10 minuteswithout applying heat. In some embodiments, the compressive pressure(squeezing) can be high compressive pressure (strong squeezing), forexample, pressure of about 5 kPa to about 52 kPa, about 10 kPa to about50 kPa, about 10 kPa to about 25 kPa, or about 25 kPa to about 50 kPa.Such squeezing treatment causes a fundamental change to the internalmorphology of the e-textile, leading to improved mechanical andelectrical properties of the printed textiles. Here, the pressing wasdone 5 minutes after printing; in other words, the printed region of thenano-textile substrate was still wet and swollen with the solvent. As acontrol experiment, we evaluated the structural compression resiliencelimit of pristine nano-textiles. The nano-textile substrate could retainits original thickness, as well as its porous non-woven fibrousstructure, after removing the pressure when the applied pressure was upto 2280 kPa (FIG. 12c ). For Ink-50% printed textiles, however, theelectrical conductivities of the strip-printed textiles wereirreversibly degraded when the applied pressure reached ˜53 kPa (FIG.12c ). Thus, we compared the effect of applied pressures of 10 kPa and50 kPa on the Ink-50% printed nano-textiles.

The squeezing treatment caused a fundamental change in the internalstructure of the printed textile. Before squeezing, the printed textileshowed tri-layer structures; with a strong presence of ˜75 μm-thickdried ink ‘skin’ at the top, the cladded layer with the permeation depthshowed 28±2 μm, whereas the non-permeated part of nano-textile remainedas pristine status (qualitatively similar to the structure shown in FIG.1g ). The cross-sectional helium-ion microscopy (HIM) images of FIGS.12a and 12b demonstrate printed samples post squeeze treatment, whereapplied pressures of 10 kPa (FIG. 12a ) and 50 kPa (FIG. 12b ) wereused. FIGS. 12a and 12b demonstrate that the squeeze treatmentfundamentally alters the cross-sectional morphology into a distincttwo-layer structure. Here, the top layer consists of rich content ofsilver, whereas its thickness is 106±6 μm at pressure of 10 kPa and188±8 μm at pressure of 50 kPa. Interestingly, the bottom layer nolonger showed fibrous structure of the nano-textile substrate, whichwere preserved in cladded layer as described in FIGS. 1g-h, 2a-c, 3c,and 10c-d . Instead, the nano-fibers seemed to be fused together bypermeated fluoroelastomer.

In some embodiments, the bottom layer can comprise a fibrous structurewherein fibers of the textile are amalgamated by a polymeric additive.The polymeric additive can be an elastomer such as, for example,polyisoprene or ethylene-vinyl acetate, or a fluoroelastomer, forexample, one or more of hexafluoropropylene (HFP), vinylidene fluoride(VDF or VF2), tetrafluoroethylene (TFE), vinylidene fluoride (VDF),hexafluoropropylene (HFP), perfluoromethylvinylether (PMVE), copolymersof hexafluoropropylene and vinylidene fluoride, terpolymers oftetrafluoroethylene, vinylidene fluoride and hexafluoropropylene, orpolytetrafluoroethylene.

The strain to failure with applied pressures of 10 kPa and 50 kPa wereincreased to 306% and 397%, respectively, compared to thewithout-pressure value of 221% (FIG. 12d ). At the same time, thetensile moduli decreased from 2.292 MPa to 1.622 MPa, then to 0.694 MPa,with increasing applied pressures from zero to 10 kPa, then to 50 KPa.The strain tolerance for electrical conductivity was significantlyimproved (FIG. 12e ). These improved mechanical and electricalproperties with applied pressure are possibly due to the alteredstructures of nano-strands in the e-textile (fusion of the strands).

E-Textile System for Strain Sensing Application. The stretchablee-textile may be adapted for use as a mechanical strain measurementsystem, which may be further applied to measure and monitorbiomechanical parameters. Strain sensors were fabricated (30 identicalsamples) using the printing method disclosed herein and were subjectedto sensitivity and reliability testing. FIG. 13a demonstrates theexponential growth of relative resistance to increasing strain (0%-25%strain, 1 sample); thus, providing a convenient means of monitoringbiomechanical motion (e.g., dynamic joint angle). The reliabilityresults demonstrated in FIG. 13b show an increase in unstrainedresistance of less than 2.5 times after each sample was subjected to4000 cycles of 20% uniaxial strain loading.

Fully Integrated E-Textile System for Surface Electromyography (sEMG)Application. The two-side e-textile biosensor was connected to anelectronic circuit for sEMG monitoring system with real-time wirelesscommunication to computer/smart phone/portable tablet (FIG. 4(a)). Thee-textile sEMG system is fully portable, lightweight, compact, and wornon human body by the patterned medical adhesives (FIG. 4(b)) Theelectrode side of the e-textile adhered well and conformed to skin,whereas the serpentine communication lines were on the other textileside, thus separated from unnecessary contact with skin. Therefore, thesEMG signal is protected from noise and crosstalk artifacts. Moreover,the conformity of the e-textile can benefit the suppression of unwantedsignals from body movements that are not associated with the muscles ofinterest when measuring.

FIG. 4(c) shows the system-level schematic of the signal transduction,filtering, processing, and transmission to real-time monitor muscleactivities. The signal of the sEMG biosensors was amplified with analogcircuit to finely stay in the input voltage period of theanalog-to-digital (A/D) converter. Then, the microcontroller regulatedthe converted signal and relayed it to the Bluetooth transceiver. Thewireless signal was sent to a computer or mobile interface for furtheranalysis.

sEMG Monitoring of Muscles Activities. The e-textile sEMG system wasworn on various body areas of a participant to monitor activities ofdifferent muscles (FIG. 5(a)). There are four body areas of interestincluding the (i) submental area, (ii) elbow, (iii) calf, and (iv)ankle. For each area, the reference electrode was located on the boneregions for robust measurement as following the study of Dr Chung & DrRieger et al. (2016).

For the sEMG assessments of the submental area, we monitored twoactivities: saliva swallowing, and mouth opening/closing separately. Theparticipant was asked to swallow saliva for 5 times, then separately toopen and close mouth for 5 times. During the swallowing incidents, FIG.5(b) shows the signal to surge to 0.5 V then shortly reduced to −0.5 V.FIG. 5(c) shows the signal during mouth opening and closing events. Itwas clearly observed that the general shape of the swallowing signal isdistinct from that of the mouth opening/closing one. In fact, notablepeaks of the signal for both events were observed.

For recording the hand crunching events, the sEMG system was located onthe elbow of the participant. The participant was asked to hold the handclose and then crunch/relax. FIG. 5(d) shows that the crunching peakswere recorded with high amplitude of 0.6 V, followed by −0.6 V for handrelaxing. Similarly, the signal of lifting toe from the calf (FIG. 5(e))and that of ankle bending from the ankle (FIG. 5(f)) were also recordedwith the short burst of signal shape. In general, the sEMG signal hadthe distinguishable shape for different muscles and their activities.

In this work, an e-textile was developed with improved mechanicaldurability and electrical performance, by jet-printing a composite inkto form ink-cladded conductive fibers inside the textile. Theink-cladding is possible because the composite ink with silver flakeswas absorbed by the hydrophilic fibers and vast number of pores insidethe textile. As a result, the printed serpentine interconnects had aconductivity of 3000-4000 S/cm, and their resistance ratio onlyincreased up to 10 times when cyclic stretching under 10%, 20%, and 30%uniaxial strains. Moreover, the e-textile was used to fabricate a fullyprinted, double-size, stretchable electronic system for sEMG and otherapplications. We anticipate that the e-textile with composite ink incouple to textile can open new opportunities of engineering innovative,practical wearable health care.

The following Examples are intended to illustrate the above inventionand should not be construed as to narrow its scope. One skilled in theart will readily recognize that the Examples suggest many other ways inwhich the invention could be practiced. It should be understood thatnumerous variations and modifications may be made while remaining withinthe scope of the invention.

EXAMPLES Example 1 Composite Ink Preparation

Fluoroelastomer (DAI-EL G801, Daikin Industries) and butanone (SigmaAldrich) were mixed with weight ratio of 1:2.55. After stirring with amagnetic stirrer for 6 hours, silver flakes (Sigma Aldrich, averageparticle size of 2-3.5 μm, ≥99.9% trace metals basis) were added to thesolution in a 2.5:1 (silver:fluoroelastomer) weight ratio and mixed withmagnetic stirrer for 4 h. 10 minutes sonication was applied to thesolution to get well-dispersed stretchable silver ink. All proceduresare carried out at room temperature.

Example 2 Printing of Composite Ink

The prepared ink (FIG. 6a ) was loaded to a syringe (FIG. 6b ) which isspecifically designed for the nScrypt Tabletop-3Dn printer (FIG. 6c ). Asheet of electrospun polyurethane nanofibers (Technical Datasheet of thematerial, see (42)) was cut in a rectangular shape of 120 mm×120 mm andpre-treated in oxygen plasma for 10 mins. The textile sheet was placedin the printer bed which was kept at room temperature during printing.To print the stretchable interconnects, the prepared ink was loaded to asyringe. For one-time printing, an amount of 10 mL was used. The printedsample (FIG. 6d ) was dried in vacuum chamber at room temperature for 8hours.

Example 3 Double-Sided E-Textile Biosensors

After printing and drying, the samples which were printed on one sidewere flipped to the other side and loaded to the printer. The sampleswere carefully positioned by a laser marking of the printer to achievewell aligned two-side circuit. After printing the circuits on two side,via interconnects (from one to another side) were formed by using a verysmall needle (⅜″ diameter) that was dip-coated by the prepared ink topuncture through the thickness of the textile one-time. The double-sidede-textile can be used for a surface electromyography (sEMG) system tomonitor muscles activities or an electroencephalography (EEG) system torecord brain waves. Other biological sensing applications of thee-textile include, for example, electrocardiography (ECG),electrooculography (EOG), respiratory rate, heart rate, mechanicalstrain, pressure, temperature, and/or vibration sensors.

CITATIONS

-   1. Stoppa, M.; Chiolerio, A. Wearable Electronics and Smart    Textiles: A Critical Review. Sensors 2014, 14, 11957-11992.-   2. Heo, J. S.; Kim, Y.-H.; Park, S. K. Recent Progress of    Textile-Based Wearable Electronics: A Comprehensive Review of    Materials, Devices, and Applications. Small 2017, 14 (3), 1703034.-   3. Wang, X.; Liu, Z.; Zhang, T. Flexible Sensing Electronics for    Wearable/Attachable. Small 2017, 13 (25), 1602790.-   4. Bae, H.; Jang, B. C.; Park, H.; Jung, S.-H.; Lee, H. M.; Park,    J.-Y.; Jeon, S.-B.; Son, G.; Tcho, I.-W.; Yu, K.; Im, S. G.; Choi,    S.-Y.; Choi, Y.-K. Functional Circuitry on Commercial Fabric via    Textile-Compatible Nanoscale Film Coating Process for Fibertronics.    Nano Letters 2017, 17 (10), 6443-6452.-   5. Yu, A.; Pu, X.; Wen, R.; Liu, M.; Zhou, T.; Zhang, K.; Zhang, Y.;    Zhai, J.; Hu, W.; Wang, Z. L. Core-Shell-Yarn-Based Triboelectric    Nanogenerator Textiles as Power Cloths. ACS Nano 2017, 11,    12764-12771.-   6. Di, J.; Zhang, X.; Yong, Z.; Zhang, Y.; Li, D.; Li, R.; Li, Q.    Carbon-Nanotube Fibers for Wearable Devices and Smart Textiles.    Advanced Materials 2016, 28, 10529-10538.-   7. Jost, K.; Stenger, D.; Perez, C. R.; McDonough, J. K.; Lian, K.;    Gogotsi, Y.; Dion, G. Knitted and screen printed carbon-fiber    supercapacitors for applications in wearable electronics. Energy &    Environmental Science 2013, 6, 2698-2705.-   8. Cherenack, K.; Zysset, C.; Kinkeldei, T.; Münzenrieder, N.;    Tröster, G. Woven Electronic Fibers with Sensing and Display    Functions for Smart Textiles. Advanced Materials 2010, 22 (45),    5178-5182.-   9. Huang, Y.; Hu, H.; Huang, Y.; Zhu, M.; Meng, W.; Liu, C.; Pei,    Z.; Ha, C.; Wang, Z.; Zhi, C. From Industrially Weavable and    Knittable Highly Conductive Yarns to Large Wearable Energy Storage    Textiles. ACS Nano 2015, 9 (5), 4766-4775.-   10. Jin, H.; Abu-Raya, Y. S.; Haick, H. Advanced Materials for    Health Monitoring with Skin-Based. Advanced Healthcare Materials    2017, 6 (11), 1700024.-   11. Maccioni, M.; Orgiu, E.; Cosseddu, P.; Locci, S.; Bonfiglio, A.    Towards the textile transistor: Assembly and characterization of an    organic field effect transistor with a cylindrical geometry. Applied    Physics Letters 2006, 89, 143515.-   12. Yoon, S. S.; Lee, K. E.; Cha, H.-J.; Seong, D. G.; Um, M.-K.;    Byun, J.-H.; Oh, Y.; Oh, J. H.; Lee, W.; Lee, J. U. Highly    Conductive Graphene/Ag Hybrid Fibers for Flexible Fiber-Type    Transistors. Scientific Reports 2015, 5, 16366.-   13. Rossi, D. D. Electronic Textiles: A Logical Step. Nature    Materials 2007, 6, 329.-   14. Hamedi, M.; Forchheimer, R.; Inganäs, O. Towards woven logic    from organic electronic fibres. Nature Materials 2007, 6, 357-362.-   15. Xie, J.; Long, H.; Miao, M. High sensitivity knitted fabric    strain sensors. Smart Materials and Structures 2016, 25, 105008.-   16. Ryu, S.; Lee, P.; Chou, J. B.; Xu, R.; Zhao, R.; Hart, A. J.;    Kim, S.-G. Extremely Elastic Wearable Carbon Nanotube Fiber Strain    Sensor for Monitoring of Human Motion. ACS Nano 2015, 9 (6),    5929-5936.-   17. Wu, X.; Han, Y.; Zhang, X.; Lu, C. Highly Sensitive,    Stretchable, and Wash-Durable Strain Sensor Based on Ultrathin    Conductive Layer@Polyurethane Yarn for Tiny Motion Monitoring. ACS    Applied Materials & Interfaces 2016, 8 (15), 9936-9945.-   18. Wang, C.; Li, X.; Gao, E.; Jian, M.; Xia, K.; Wang, Q.; Xu, Z.;    Ren, T.; Zhang, Y. Carbonized Silk Fabric for Ultrastretchable,    Highly Sensitive, and Wearable Strain Sensors. Advanced Materials    2016, 28 (31), 6640-6648.-   19. Zysset, C.; Nasseri, N.; Büthe, L.; Münzenrieder, N.; Kinkeldei.    Textile Integrated Sensors and Actuators for near-Infrared    Spectroscopy. Optics Express 2013, 21, 3213-3224.-   20. Yang, Y.-L.; Chuang, M.-C.; Lou, S.-L.; Wang, J. Thick-Film    Textile-Based Amperometric Sensors and Biosensors. Analyst 2010,    135, 1230-1234.-   21. Kim, K. N.; Chun, J.; Kim, J. W.; Lee, K. Y.; Park, J.; Kim, S.;    Wang, Z. L. Highly Stretchable 2D Fabrics for Wearable Triboelectric    Nanogenerator under Harsh Environments. ACS Nano 2015, 9 (6),    6394-6400.-   22. Zhang, Z.; Chen, Y.; Debeli, D. K.; Guo, J. S. Facile Method and    Novel Dielectric Material Using a Nanoparticle-Doped Thermoplastic    Elastomer Composite Fabric for Triboelectric Nanogenerator    Applications. ACS Applied Materials & Interfaces 2018.-   23. Zeng, W.; Tao, X.-M.; Chen, S.; Shang, S.; Chan, H. L. W.;    Choy, S. H. Highly durable all-fiber nanogenerator for mechanical    energy harvesting. Energy & Environmental Science 2013, 6,    2631-2638.-   24. Seung, W.; Gupta, M. K.; Lee, K. Y.; Shin, K.-S.; Lee, J.-H.;    Kim, T. Y.; Kim, S.; Lin, J.; Kim, J. H.; Kim, S.-W. Nanopatterned    Textile-Based Wearable Triboelectric Nanogenerator. ACS Nano 2015, 9    (4), 3501-3509.-   25. Zhong, J.; Zhang, Y.; Zhong, Q.; Hu, Q.; Hu, B.; Wang, Z. L.;    Zhou, J. Fiber-Based Generator for Wearable Electronics and Mobile    Medication. ACS Nano 2014, 8 (6), 6273-6280.-   26. Le, V. T.; Kim, H.; Ghosh, A.; Kim, J.; Chang, J.; Vu, Q. A.;    Pham, D. T.; Lee, J.-H.; Kim, S.-W.; Lee, Y. H. Coaxial Fiber    Supercapacitor Using All-Carbon Material Electrodes. ACS Nano 2013,    7 (7), 5940-5947.-   27. Meng, Q.; Wang, K.; Guo, W.; Fang, J.; Wei, Z.; She, X.    Thread-like Supercapacitors Based on One-Step Spun Nanocomposite    Yarns. Small 2014, 10 (15), 3187-3193.-   28. Yoon, J.; Jeong, Y.; Kim, H.; Yoo, S.; Jung, H. S.; Kim, Y.;    Hwang, Y.; Hyun, Y.; Hong, W.-K.; Lee, B. H.; Choa, S.-H.; Ko, H. C.    Robust and stretchable indium gallium zinc oxide-based electronic    textiles formed by cilia-assisted transfer printing. Nature    Communications 2016, 7, 11477.-   29. Harnett, C. K.; Zhao, H.; Shepherd, R. F. Stretchable Optical    Fibers: Threads for Strain-Sensitive. Advanced Materials    Technologies 2017, 2 (9), 1700087.-   30. Kim, D.-H.; Lu, N.; Ma, R.; Kim, Y.-S.; Kim, R.-H.; Wang, S.;    Wu, J.; Won, S. M.; Tao, H.; Islam, A.; Yu, K. J.; Kim, T.-I.;    Chowdhury, R.; Ying, M.; Xu, L.; Li, M.; Chung, H.-J.; Keum, H.;    McCormick, M.; Liu, P.; Zhang, Y.-W.; Omenetto, F. G.; Huang, Y.;    Coleman, T.; Roger, J. A. Epidermal Electronics. Science 2011, 333,    838.-   31. Chung, H.; Sulkin, M. S.; Kim, J.; Goudeseune, C.; Chao, H.;    Song, J. W.; Yang, S. Y.; Hsu, Y.; Ghaffari, R.; Efimov, I. R.;    Rogers, J. A. Stretchable, Multiplexed pH Sensors With    Demonstrations on Rabbit and Human Hearts Undergoing Ischemia.    Advanced Healthcare Materials 2014, 3 (1), 59-68.-   32. Gao, W.; Emaminejad, S.; Nyein, H. Y. Y.; Challa, S.; Chen, K.;    Peck, A.; Fahad, H. M.; Ota, H.; Shiraki, H.; Kiriya, D.; Lien,    D.-H.; Brooks, G. A.; Davis, R. W.; Javey, A. Fully integrated    wearable sensor arrays for multiplexed in situ perspiration    analysis. Nature 2016, 529, 509.-   33. Yokota, T.; Inoue, Y.; Terakawa, Y.; Reeder, J.; Kaltenbrunner,    M.; Ware, T.; Yang, K.; Mabuchi, K.; Murakawa, T.; Sekino, M.; Voit,    W.; Sekitani, T.; Someya, T. Ultraflexible, large-area,    physiological temperature sensors for multipoint measurements. Proc.    Natl. Acad. Sci. USA 2015, 112, 14533.-   34. Drack, M.; Graz, I.; Sekitani, T.; Someya, T.; Kaltenbrunner,    M.; Bauer, S. An imperceptible plastic electronic wrap. Advanced    Materials 2015, 27 (1), 34-40.-   35. Lipomi, D. J.; Vosgueritchian, M.; Tee, B. C.-K.; Hellstrom, S.    L.; Lee, J. A.; Fox, C. H.; Bao, Z. Skin-like pressure and strain    sensors based on transparent elastic films of carbon nanotubes.    Nature Nanotechnology 2011, 6, 788-792.-   36. Kim, B.-S.; Lee, S. W.; Yoon, H.; Strano, M. S.; Shao-Horn, Y.;    Hammond, P. T. Pattern Transfer Printing of Multiwalled Carbon    Nanotube Multilayers and Application in Biosensors. Chemistry of    Materials 2010, 22 (16), 4791-4797.-   37. Cottet, D.; Grzyb, J.; Kirstein, T.; Tröster, G. Electrical    characterization of textile transmission lines. IEEE Trans. Adv.    Packag. 2003, 26, 182-190.-   38. Bhat, N. V.; Seshadri, D. T.; Radhakrishnan, S. Preparation,    Characterization, and Performance of Conductive Fabrics:    Cotton+PANi. Textile Research Journal 2004, 74 (2), 155-166.-   39. Matsuhisa, N.; Kaltenbrunner, M.; Yokota, T.; Jinno, H.;    Kuribara, K.; Sekitani, T.; Someya, T. Printable elastic conductors    with a high conductivity for electronic textile applications. Nature    Communications 2015, 6, 7461.-   40. Jin, H.; Matsuhisa, N.; Lee, S.; Abbas, M.; Yokota, T.;    Someya, T. Enhancing the Performance of Stretchable Conductors for    E-Textiles by Controlled Ink Permeation. Advanced Materials 2017,    29, 1605848.-   41. Richards, H. R. Thermal Degradation of Fabrics and Yarns—Part I:    Fabrics. Journal of the Textile Institute 1984, 75 (1), 28-36.-   42. SNS NANOFIBER TECHNOLOGY, LLC, 2018.    www.snsnano.com/pdf/PR-014%20NANOSAN-Sorb%20Technical%20Data%20Sheet.pdf    (accessed Mar. 29, 2018).

While specific embodiments have been described above with reference tothe disclosed embodiments and examples, such embodiments are onlyillustrative and do not limit the scope of the invention. Changes andmodifications can be made in accordance with ordinary skill in the artwithout departing from the invention in its broader aspects as definedin the following claims.

All publications, patents, and patent documents are incorporated byreference herein, as though individually incorporated by reference. Nolimitations inconsistent with this disclosure are to be understoodtherefrom. The invention has been described with reference to variousspecific and preferred embodiments and techniques. However, it should beunderstood that many variations and modifications may be made whileremaining within the spirit and scope of the invention.

What is claimed is:
 1. An electronic textile apparatus comprising: a) aporous textile having fibers, a surface, and an opposite surface; b) apatterned electrically conductive wire that coats a portion of thefibers at the surface of the textile; c) an electrode that coats aportion of the fibers at the opposite surface of the textile; and d) anelectrically conductive interconnect that coats a portion of the fiberswithin the textile, disposed between the surface and the oppositesurface of the textile, and in contact with the wire and the electrode;wherein the wire, the electrode and the interconnect comprise anelastomer and metal particles.
 2. The apparatus of claim 1 wherein thefibers are synthetic fibers such as a fiber comprising electrospunpolyurethane.
 3. The apparatus of claim 1 wherein the textile has a poresize of about 1 micron to about 100 microns.
 4. The apparatus of claim 1wherein the surface and the opposite surface of the textile has coatedfibers up to a depth of about 100 microns within the textile.
 5. Theapparatus of claim 1 wherein the elastomer is a fluoropolymer or afluorocopolymer.
 6. The apparatus of claim 1 wherein the metal particleshave a diameter of up to about 10 microns.
 7. The apparatus of claim 1wherein the textile has an electrical resistance ratio of about 10 orless than 10 after about 1000 cyclic stretches from zero to about 30%strain at a rate of about 4% strain per second.
 8. An electronic textileapparatus comprising: a) a porous textile having fibers, a surface, andan opposite surface; b) a patterned electrically conductive pad thatcoats a portion of the fibers at the surface of the textile; c) aconductive pad that has two-layer structure, where the top layercomprises conductive material and the bottom layer shows a joinedfibrous structure wherein the fibers of the textile are amalgamated by apolymeric additive; wherein the wire, the electrode and the interconnectcomprise an elastomer and metal particles.
 9. The apparatus of claim 8wherein the fibers are synthetic fibers such as a fiber comprisingelectrospun polyurethane.
 10. The apparatus of claim 8 wherein thetwo-layer structure is prepared by squeezing synthetic fibers in thepresence of printed conductive ink material, wherein the conductive inkmaterial comprises about 1 part to about 5 parts of (a) afluorocopolymer, about 1 part to about 5 parts of (b) an organicsolvent, and about 1 part to about 5 parts of (c) metal flakes.
 11. Theapparatus of claim 8 wherein the elastomer is a fluoropolymer or afluorocopolymer.
 12. The apparatus of claim 8 wherein the metalparticles have a diameter of up to about 10 microns.
 13. The apparatusof claim 8 wherein the textile has an electrical resistance ratio ofabout 10 or less than 10 after about 1000 cyclic stretches from zero toabout 30% strain at a rate of about 4% strain per second.
 14. An inkcomposition comprising about 1 part to about 5 parts of (a) afluorocopolymer, about 1 part to about 5 parts of (b) an organicsolvent, and about 1 part to about 5 parts of (c) metal flakes.
 15. Thecomposition of claim 14 wherein the composition has a ratio of(a):(b):(c) of about 4:3:3.
 16. The composition of claim 14 wherein themetal flakes are silver flakes having a diameter of about 1 micron toabout 10 microns.
 17. The composition of claim 14, wherein the size ofthe metal flakes can be controlled to adjust the level of inkpermeation.
 18. The composition of claim 14 wherein the organic solventis a ketone.
 19. A method for fabricating a stretchable electronictextile from the composition of claim 14 comprising: a) printing acircuit with the ink composition of claim 14 on a porous textile havingfibers; wherein a wire is printed on a surface of the textile, and anelectrode is printed on the opposite surface of the textile; b)inserting the composition of claim 14 into the textile to provide anelectrical contact between the wire and the electrode, thereby forming acompleted circuit; c) drying the completed circuit; wherein theprintable ink coats a portion of the fibers that forms the completedcircuit, and the textile has an electrical resistance ratio of about 10or less than 10 after about 1000 cyclic stretches from zero to about 30%strain at a rate of about 4% strain per second.
 20. The method of claim19 wherein the fibers are synthetic fibers such as a fiber comprisingelectrospun polyurethane and the textile has a pore size of about 1micron to about 100 microns.
 21. The method of claim 19 wherein thecompleted circuit comprises a circuit for a wearable medical device. 22.The method of claim 19 wherein the completed circuit comprises a circuitfor surface electromyography.
 23. The method of claim 19 wherein thecompleted circuit is configured to sense at least one ofelectromyography (EMG), electroencephalography (EEG),electrocardiography (ECG), electrooculography (EOG), respiratory rate,heart rate, mechanical strain, pressure, temperature, vibration, andcombinations thereof.
 24. The method of claim 19 wherein the completedcircuit is configured to provide stimulus of at least one type from thegroup consisting of visual, audio, mechanical, electrical, temperature,and combinations thereof.